1. Field of the Invention
The present invention relates to a developing apparatus for use in the electrophotographic copying process or the like to convert to visible images electrostatic latent images formed on an electrostatic latent image bearing member.
2. Description of the Prior Art
Developing apparatus have heretofore been provided which comprise a developing sleeve made of aluminum or the like and having a magnet fixedly provided therein, and a drivingly rotatable developer agitating roller (such as a bucket roller or screw roller) for supplying a developer to the outer periphery of the sleeve. The developing sleeve is adapted to support the developer thereon and to transport the developer to a developing station opposed to an electrostatic latent image bearing member, whereby an electrostatic latent image formed on the surface of the bearing member is developed to a visible image.
Generally with developing apparatus, the developer passing through the developing station and used for development has a reduced toner concentration, so that the developer needs to be temporarily removed from the outer periphery of the developing sleeve and, so to speak, replaced by a fresh portion of developer supplied to the sleeve peripheral surface.
Accordingly, it is conventional practice to provide a scraper in pressing contact with the outer periphery of the developing sleeve at a location downstream from the developing station for scraping off the developer used as disclosed in U.S. Pat. No. 4,054,230.
The outer peripheral surface of many developing sleeves has minute projections or identations formed as by sandblasting to transport the developer with improved efficiency. When the scraper is held in pressing contact with the sleeve surface in this case, the scraper wears the developing sleeve markedly and causes the developer to clog up the minute indentations by the pressing contact. The accumulation of developer solidifies with time, no longer permitting the sleeve surface to support the developer as uniformly distributed thereover.
The conventional apparatus has another problem in that the scraper, when provided, imposes a limitation on the position where the agitating roller and the like are to be installed, rendering the apparatus large-sized.